A027166 a(n) = Sum_{0<=j<=i<=n} A027157(i, j).

1, 4, 14, 36, 103, 248, 684, 1624, 4445, 10524, 28762, 68060, 185955, 439984, 1202072, 2844144, 7770361, 18384884, 50228454, 118841812, 324681887, 768205608, 2098776772, 4965759176, 13566706389, 32099171980, 87696568754, 207492309516, 566879531803

Offset: 0

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Colin Barker, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (2,5,-12,9,-6,3).

Crossrefs

Partial sums of A027164.

Programs

Mathematica

LinearRecurrence[{2,5,-12,9,-6,3},{1,4,14,36,103,248},30] (* Harvey P. Dale, Apr 18 2019 *)

PARI

Vec((1+x)^2/((1-x)^2*(1-6*x^2-3*x^4)) + O(x^40)) \\ Colin Barker, Feb 20 2016

Formula

From Colin Barker, Feb 20 2016: (Start)

a(n) = 2*a(n-1)+5*a(n-2)-12*a(n-3)+9*a(n-4)-6*a(n-5)+3*a(n-6) for n>5.

G.f.: (1+x)^2 / ((1-x)^2*(1-6*x^2-3*x^4)).

(End)